ADDITIVE RELATIONS OF THE BOILING POINT 51 



the boiling point 1 . In the first place, at corresponding 

 temperatures the ratio between volumes of liquid and 

 vapour is constant, if no molecular association occurs. 



ZL* 



If further the saturated vapour is dilute enough, then F 

 standing for the molecular volume, we have 



V d 2 , 



so that 



T= *kAPV t . 



The assumption that P is one atmosphere for corre- 

 sponding temperatures, makes kPA constant, and therefore 

 the boiling point T proportional to the molecular volume V L . 



The radical test of this, by means of the elements them- 

 selves, is partly possible with the data in existence. 

 Thus: 



Boiling point of hydrogen . - 2 3 8C. = 35 abs. 2 (H = 17) 



Simple binary compounds : 



